The disclosed technology relates to water soluble, or partially water soluble, chain transfer agents for preparing water soluble polymers by Reversible Addition-Fragmentation Chain Transfer (“RAFT”) polymerization in an aqueous medium.
Many references for Reversible Addition-Fragmentation Chain Transfer (“RAFT”) polymerizations involving Chain Transfer Agents (“CTA”) teach polymerizations done in organic solvents such as toluene or 1,4-dioxane in order to prepare water-based polymers (meaning either water soluble polymers or emulsions). While such organic solvents are certainly sufficient for polymerization, they pose both a health risk and a fire hazard, and thus large scale commercialization using such solvents is not desired. Further, when such organic solvent are employed for making water soluble polymers, the organic solvent must be stripped to provide a useful water-soluble polymer, which adds additional hazard as well as time and resources.
A more preferred way of synthesizing water soluble polymers is to make the polymers directly in water with a water soluble CTA. This has been demonstrated many times in the academic literature. In one report, Matsuno, Ryosuke; Goto, Yusuke; Konno, Tomohiro; Takai, Madoka; Ishihara, Kazuhiko Journal of Nanoscience and Nanotechnology (2009), 9(1), 358-365, researchers used CTA-Na that was hydrophobically associated to a modified quantum dot (QD) in water to build a QD supported biopolymer. In this example the researchers took advantage of the surfactant properties of CTA-Na to help stabilize the QD and subsequent polymer that was grown out from the core.
What is needed is an economically feasible way to control polymerization of water soluble monomers such as AMPS™, acrylamide, acrylic acid, etc., in aqueous solutions.